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bnplay-audio-api.html
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bnplay-audio-api.html
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<!doctype html>
<html>
<head>
<title>BNPlay - Audio API version</title>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<link rel="icon" href="favicon.png" />
<style type="text/css">
body,
td,
th {
font-family: sans-serif;
}
body {
background-color: #222;
color: #ccc;
}
.text-center {
text-align: center;
}
.btn-ctrl {
background-color: #000;
color: #ccc;
border: 1px solid #888;
padding: 20px 30px;
font-weight: bold;
}
.btn-ctrl-loading {
color: #c60;
border: 1px solid #f80;
}
.btn-ctrl-error {
color: #c00;
border: 1px solid #f00;
}
</style>
<script type="text/javascript">
// Brown Noise Player
class BNP {
static audioCtx = new AudioContext();
static audioData;
static source = null;
static async getSampleFromWeb() {
const response = await fetch(
// This URL has CORS enabled
"https://dmotte.github.io/bnplay/bn-sample.flac",
);
if (!response.ok) throw new Error("HTTP error " + response.status);
return await response.arrayBuffer();
}
static async getSample() {
const dbName = "bnplay-cache",
storeName = "files",
itemName = "bn-sample.flac";
const db = await new Promise((resolve, reject) => {
const req = indexedDB.open(dbName, 1);
req.onerror = (event) => {
reject(new Error(`Error opening IndexedDB database ${dbName}`));
};
req.onupgradeneeded = (event) => {
const db = event.target.result;
if (!db.objectStoreNames.contains(storeName))
db.createObjectStore(storeName);
};
req.onsuccess = (event) => {
resolve(event.target.result);
};
});
const transaction = db.transaction(storeName, "readonly");
const store = transaction.objectStore(storeName);
let buffer = await new Promise((resolve, reject) => {
const req = store.get(itemName);
req.onerror = (event) => {
reject(
new Error(
`Error getting item ${itemName} from store ${storeName} from IndexedDB database ${dbName}`,
),
);
};
req.onsuccess = (event) => {
resolve(event.target.result);
};
});
if (!buffer) {
buffer = await this.getSampleFromWeb();
// We cache the audio file indefinitely because we assume that it
// will never change
const transaction = db.transaction(storeName, "readwrite");
const store = transaction.objectStore(storeName);
store.put(buffer, itemName);
}
return buffer;
}
static async initialize() {
this.audioData = await this.audioCtx.decodeAudioData(
await this.getSample(),
);
}
static isPlaying() {
return this.source !== null;
}
static play() {
if (this.isPlaying()) return;
this.source = new AudioBufferSourceNode(this.audioCtx);
this.source.buffer = this.audioData;
this.source.connect(this.audioCtx.destination);
this.source.loop = true;
this.source.start(0);
}
static stop() {
if (!this.isPlaying()) return;
this.source.stop();
this.source = null;
}
static toggle() {
if (this.isPlaying()) this.stop();
else this.play();
}
}
class UI {
static load() {
const btnToggle = document.getElementById("btnToggle"),
divStatus = document.getElementById("divStatus");
return BNP.initialize()
.then(() => {
btnToggle.classList.remove("btn-ctrl-loading");
btnToggle.removeAttribute("disabled");
this.update();
})
.catch((error) => {
console.log(error);
btnToggle.classList.remove("btn-ctrl-loading");
btnToggle.classList.add("btn-ctrl-error");
divStatus.textContent = error;
btnToggle.value = "ERROR";
});
}
static update() {
const btnToggle = document.getElementById("btnToggle"),
divStatus = document.getElementById("divStatus");
if (BNP.isPlaying()) {
divStatus.textContent = "Playing...";
btnToggle.value = "STOP";
} else {
divStatus.textContent = "Stopped.";
btnToggle.value = "PLAY";
}
}
static toggle() {
BNP.toggle();
this.update();
}
}
</script>
</head>
<body
onload="UI.load()"
onkeypress="if (event.key == ' ') btnToggle.click();"
>
<div class="text-center">
<h1>Brown noise</h1>
<p><i>Audio API version</i></p>
<br />
<div id="divStatus">Please wait...</div>
<br />
<input
type="button"
id="btnToggle"
value="Loading..."
class="btn-ctrl btn-ctrl-loading"
onfocus="this.blur()"
onclick="UI.toggle()"
disabled="disabled"
/>
</div>
</body>
</html>